1. Field of the Invention
The invention relates in general to a method of controlling rotating speed of an optical drive, and more particularly to a method of controlling rotating speed of an optical drive according to the frequency and duration time of issuing a plurality of reading requests by a host.
2. Description of the Related Art
Along with the continual development of personal computers, the transmission speed and capacity of accompanied peripheral devices also become higher and higher. Therefore, the high-speed optical drive is still a mainstream product in terms of optical drives.
However, problems such as power consuming, vibrations and high energy consuming would arise if a high-speed optical drive is under high-speed operation, so the high-speed optical drive cannot continually maintain high-speed operation in practical operation. So an internal mechanism is needed for the high-speed optical drive to appropriately adjust the rotating speed of the optical drive.
Generally speaking, whether to increase the rotating speed of the spindle motor of an optical drive or not is determined according to the number of occurrences of erroneous data decoding. For example, the rotating speed of an optical drive may be further increased so the accessing of the data stored in the optical disk may be speeded up, if the number of occurrences of erroneous data decoding is less than a predetermined value when the spindle motor of the optical drive is rotating at a specific rotating speed within a fixed time period. To the contrary, the rotating speed of the optical drive will be lowered down, if the number of occurrences of erroneous data decoding is larger than the predetermined value when the spindle motor of the optical drive is rotating at a specific rotating speed within a fixed time period.
However, the above determination method cannot actually reflect the needs of an optical drive or a host. For example, when an optical drive is rotating at a low speed and a host is issuing reading requests in a low frequency, the data reading speed of the optical drive may be matched with the issuing speed of reading requests of the host. Suppose the optical drive has no error in data decoding, the rotating speed of the spindle motor of the optical drive must be increased according to the mechanism of determining the rotating speed in the prior art. However, it is inappropriate to increase the rotating speed of the spindle motor of the optical drive when the data reading speed of the optical drive is matched with the issuing speed of reading requests of the host. So the mechanism of determining the rotating speed in the prior art still needs to be improved.